Every year, vehicle crashes cause millions of deaths and serious injuries worldwide among occupants of automobiles, planes, trains and other modes of transportation. For example, in the United States alone, roughly 2.7 million automobile injuries occur annually, causing approximately $230 billion damage.
Occupants of automobile front seats account for about 90 percent of all auto fatalities. Importantly, about 45 percent of occupants killed in automobile accidents wear seat belts. Only 24 percent of tested car seats obtained a satisfactory rating in a study by the Insurance Institute for Highway Safety (IIHS) reported in 2007. Yet, some safety experts have identified vehicle seats as one of the most potentially effective life saving devices available, and have encouraged automobile manufacturers to improve seating systems in terms of comfort, ergonomics and safety.
Currently, auto seat designers trying to develop safer seating systems are pursuing two conflicting approaches. One general approach is to increase rigidity of the seat structure. The second approach is to use plastically deformable materials to produce yielding seat components.
The automotive industry concentrates its attention mostly on the protection of occupants during rear end collisions, even though whiplash injuries from rear end collisions cause only about 25 percent of all expenditures paid by insurance agencies.
Some successful improvements to occupant protection have derived from recently developed pre-crash detection technology that determines when a crash is imminent and activates vehicle subsystems for corrective action before impact occurs.
Numerous measures have been implemented in the vehicle manufacturing industries over the past decades in attempts to reduce deaths, injuries and monetary damages resulting from vehicle crashes. Examples include seat belts, airbags, head restraints, improved compartment design, and exterior changes, such as vehicle crumple zones. While being helpful in some situations, some measures are known to exacerbate injuries in other situations. For example, in some vehicle crashes, the shoulder sash of a seat belt system causes undesirable pressure to the throat, neck or head of the occupant. In some vehicle crashes, an airbag interferes with operator control of an automobile or actually injures a seat occupant.
Generally, designers of vehicle interiors and vehicle seats accept an occupant's pre-impact posture as uncontrolled. Some vehicle seat designers have attempted to mitigate crash effects using various alternative approaches, such as energy absorption and occupant posture control.
U.S. Pat. No. 6,631,955, issued Oct. 14, 2003, to Humer et al., discloses a variable movement headrest to provide head support to a vehicle occupant by quickly decreasing the gap between an occupant's head and the headrest. U.S. Pat. No. 7,588,289, issued Sep. 15, 2009, to Boström et al., discloses a vehicle seat having a headrest that moves forward in a manner depending on the severity of an impact. U.S. Patent Application Publication No. 2009/0108645, published Apr. 30, 2009, by Nilakantan, teaches an active head restraint system that is actuated before an occupant is thrown rearward against a backrest. U.S. Pat. No. 6,022,074, issued Feb. 8, 2000, to Swedenklef, teaches a seat suitable for damping the effects of a high-pressure impact against the seat backrest by the occupant of the seat, which seat includes a backrest element mounted on a squab for pivotal movement relative to the squab.
U.S. Pat. No. 7,354,106, issued Apr. 8, 2008, to Dennis, discloses a vehicle safety seat useful in aircraft and small sea-going vessels, in which a seated occupant is accelerated upward a fraction of a second after initial crash impact, thereby reducing downward velocity and avoiding compressive axial forces on the spine. U.S. Pat. No. 5,553,924, issued Sep. 10, 1996, to Cantor et al., discloses a contoured seat bottom with an energy-absorbing foam layer covered by a second foam layer having a rate sensitive compression characteristic.
U.S. Pat. No. 3,953,068, issued Apr. 27, 1976, to Porsche et al., discloses a passenger seat having a backrest pivotally attached to a seat rest in which energy absorption devices dissipate and absorb collision and/or deceleration forces acting on the seat or a passenger in the seat. U.S. Pat. No. 5,556,160, issued Sep. 17, 1996, to Mikami, discloses a seat bottom that rotates from a seating position to an inclined position, in which the rear of the seat bottom is below the knees of a seated person, in order to prevent the seated person being flung forward by forces of inertia. U.S. Pat. No. 6,851,747, issued Feb. 8, 2005, to Swierczewski, discloses a collapsible vehicle safety seat designed upon impact to lower the center of gravity of an occupant.
There is a need for vehicle seats that protect vehicle occupants, reduce injuries, are cost effective, and are compatible with conventional vehicle equipment, compartment spaces and designs.